It has been long known that sawchains can be designed to be sharpened by application of a shaped block of abrasive material against the top of the chain when it runs idling around the drive sprocket of the chain saw. Such devices save time, because the chain needs not be removed, and no filing gauge has to be mounted on the guidebar. It is also simpler for unexperienced users, since no knowledge of filing angles is needed.
In spite of this such sawchains have only found limited use, since they have severe drawbacks in other respects.
They all have in common that the height of the cutter links decreases quickly, and no more than 6 to 8 resharpenings can be made before the sawchain must be discarded, because every resharpening removes a layer corresponding to the radius of the worn edge, circa 0.25 mm. This compares with 20 to 25 resharpenings in the lengthwise direction for a conventional sawchain. There are, however, certain applications such as for temporary use, for use as a hobby tool and for use in vehicle-born harvesters and fellers, when the number of resharpenings possible is unimportant compared to the speed and convenience in resharpening.
The present invention concerns a sawchain which can be resharpened by grinding the tops of the cutter links, without the drawbacks that until now have prevented a more common use of prior top-sharpened sawchains.